Technology

Backup batteries for phones and tablets have become smaller and more powerful, with some offering about two and a half charges in a package a little larger than two packs of playing cards. The makers of a new fuel cell demonstrated at the Consumer Electronics Show in Las Vegas say it has them beat by a factor of five.

The Nectar Mobile Power System is a fuel cell powered by a butane cartridge. It is roughly the size of a small but thick paperback book.

According to Nectar, it carries 10 to 14 full charges for a phone or tablet. The company is calling that two weeks of power, based on one recharge a day.The unit is fairly lightweight and does not produce much heat. While charging a phone, the case did not feel much warmer than room temperature — far cooler than the average laptop battery while in use.

Although the charger is powered by butane, you cannot pump it full of lighter fluid to recharge. The butane comes in "Nectar Pods," small reservoirs that are approved to be carried on aircraft and can be tossed in the recycling bin when empty.Nectar will be initially available at Brookstone stores this summer at a wallet-lightening price of $300. Refill pods will be $10 each.